When adding a .NET barcode control (or .NET DLL) to a form, the following errors may occur:

• Object reference not set to an instance of an object.
• The .NET assembly ‘????.dll’ could not be found.
• Cannot add Barcode Control to Toolbox or Form in Visual Studio .NET

Solution(s):

If the barcode control (or .NET DLL) cannot be added to the project, make sure the proper control is used for the type of application.

• The ASP.NET Web Server Control is only compatible with Web Applications.
• The .NET Windows Forms Control only works in Local Windows Applications.

If the proper control is used in the appropriate application and it still does not function, delete all files from %temp%, remove the control from the project, and reinstall the control.